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Abstract
Asthma and allergic reactions result in inflamed and swollen lung airways. Asthma is of two types, atopic and non-atopic. The asthma symptoms include excessive production of mucus, coughing, tightness in chest, wheezing, and difficulty in breathing. The triggers for atopic asthma are allergens and the hyper-responsiveness of IgE immunoglobulin. Genetic factors are involved in non-atopic asthma that relies on the propensity of developing asthma and hypersensitivity of airways. Epithelial cytokines, macrophage, eosinophils, and T cells collectively influence the fibroblast production resulting in muscle mutagenesis and bronchial hyper-responsiveness. For the diagnosis of asthma, several tests are suggested, such as Peak expiratory flow test, spirometry, and skin tests. The treatment for asthma ranges from oral pharmaceutical agents to anti-inflammatory bronchodilator and nebulizers. Conventional treatments are not sufficient to treat non-atopic asthma. Self-management and self-assessment are the best way to prevent asthma. Underestimation of the condition may be life threatening. Early prophylaxis and self-care reduce the severity of asthma as well as decline the morbidity rate.
Background and Disease Pathology
Asthma is a chronic condition that entails the inflammation and narrowing of lung airways. The severity of atopic asthma is determined by the response to allergens and viral factors (Dunnill, 1960). The pathogenesis of atopic asthma includes musculoskeletal spasms, anemia, tachypnea, and tachycardia that may result in severe cardiovascular impediments. Genetic factors are responsible for non-allergic asthma that relies on two determinants: the aptitude of developing asthma (atopy) and hypersensitivity of airways (Barnes, 1996). An abnormal gene located on an 11th chromosome has been found to be responsible for atopy that encodes a section of immunoglobin IgE receptor (Barnes, 1996). Eosinophilia linked with mucociliary escalator and extreme detaching of bronchial epithelium are the characteristics of allergic as well as non-allergic asthma (Frigas & Gleich, 1986).
The pathophysiology of asthma is comprehensive that includes inflammation, irregular airflow obstruction, and bronchial hyperresponsiveness. The T cells, especially TH2 also play a significant role in both types of asthma (Larché, Robinson & Kay, 2003). TH2 cytokines are capable of altering the airway irritation; predominantly IL-13 that is associated with hypersensitivity. Furthermore, the transcription factors regulating TH1 and TH2, advocates the TH2 involvement because GATA3 is excessively expressed while T-bet is under-expressed in the asthmatic airways (Larché, Robinson & Kay, 2003). These obstructions hinder the functioning of other ciliated cells and cause accumulation of bronchial secretions in asthmatic conditions (Dunnill, 1960; Barnes, 1996)
Numerous eosinophil products release cytotoxins that can damage the epithelial cells (Barnes, 1996). Moreover, active eosinophils produce collagenases that harm the basement membrane and mast cell generated proteases slack the intercellular adhesion. Thus the disturbed epithelium results in the bronchial hyper-responsiveness (Frigas & Gleich, 1986). Epithelial cytokines, eosinophils, macrophage and T cells together impact the fibroblast production and facilitate muscle mutagenesis. These incidences make bulky airway causing muscle hypertrophy and hyperplasia that in turn induce bronchial hyper-responsiveness (Larché, Robinson & Kay, 2003).
Signs & Symptoms
Inflamed airways are the hallmark of asthma that makes these narrow passages very sensitive and constricted. These structural changes result in muscle tightening and less intake of air, which are considered as the prime asthma symptoms (Barnes, 1996). Excessive production of mucus develops asthmatic symptoms, which are coughing, wheezing, and tightness in chest, shortness, and difficulty in breathing (National Asthma Education, 1997). Congested nasal turbinates, sleeplessness due to breathing difficulty and augmented respiratory rate are several other signs. Nonatopic asthma is evidenced by characteristics, such as later onset and high extent of severity (National Asthma Education, 1997).
Diagnostic Tests and Treatment
There are several tests that are prescribed according to the patient’s condition, to confirm asthma or to examine the progression level of asthma (National Asthma Education, 1997).
Peak expiratory flow test- The peak expiratory flow (PEF) is prescribed to detect the progression scale of the pre-diagnosed disease.
Spirometry- Spirometry is useful in confirming the presence of asthma from other lung conditions. It evaluates the health of lung's physiology.
Testing of airway inflammation-It helps to assess the inflammation of airways via either exposing nitric oxide or analyzing a mucus sample.
Testing of Airways responsiveness- Airways responsiveness measures the sensitivity of airways on the disclosure of a trigger. It is an advanced level test that is performed after the failure of simple tests.
Some skin allergy tests- Skin tests and blood tests also are suggested to confirm the link between asthma with specific allergens. Negative skin tests to common aeroallergens are valuable to distinguish between non-atopic and atopic asthma (National Asthma Education, 1997). Positive skin test indicates the IgE antibodies production against the exposure to allergens (Romanet‐Manent et al., 2002). At advanced level radiographic testing, such as X-ray, MRI can also suggested to detect any alterations in musculoskeletal structure due to prolonged asthmatic conditions, like bone thickness (National Asthma Education, 1997).
Nonatopic can not be treated by conventional treatments (Romanet‐Manent et al., 2002). Asthma treatment involves various ranges from oral pharmaceutical agents to anti-inflammatory bronchodilator (National Asthma Education, 1997). The introduction of Anti-Inflammatory Agents, corticosteroids or cromolyn sodium at an early stage is highly effective and prescribed to treat inflammation, swelling and thick mucus of the airways. Early prophylaxis averts the bronchodilator therapy as well as morbidity (Barnes, 1996). Bronchodilators have substances that keep the symptoms under control through managing the inflammation and opening up the airways. Asthma Nebulizers are a suitable option to deliver the drug to all age group.
Busse et al., have conducted a study on human recombinant anti-IgE mAb, omalizumab that can block the interplay of IgE with mast cells and basophils by making a complex with IgE (Busse et al., 2001). This interaction is valuable for treating asthma as a promising therapeutic approach because IgE is an essential mediator in the initiation and progression of allergic reactions (Busse et al., 2001). On the basis of IgE role in asthma, monoclonal antibody attenuation is also proposed in treating asthma (Boulet et al., 2012). Furthermore, the investigation of neutrophils role in severe asthma is under process and experts are hopeful with its potent clinical advantages (Nair et al., 2012).
Asthma Management and Prevention
Key points of asthma management include maintenance of pulmonary function and prevention of chronic symptoms like wheezing, and coughing. Self-assessment is the principal way to monitor asthma (National Asthma Education, 1997). Underestimation of the severity of Asthma, delayed treatment and improper management often results in death. Multiple evidence-based practices have suggested that early prophylaxis and self-management of asthma not only reduces the severity of disease but can also decline the morbidity rate (Lahdensuo et al., 1996; Beasley, Cushley & Holgate, 1989). The survey conducted by Rabe and co-workers concluded that the current state of asthma control in patients imitates the extent to which guidelines are executed (Rabe et al., 2000). The Better practice of breathing can reduce the intensity of symptoms and relieve the problems. Complimentary treatments like regular moderate exercise, hydrotherapy, and aerobics can help in relieving the symptoms (National Asthma Education, 1997).
Mortality & Morbidity Rate
Western Europe faces a maximum prevalence of asthma, 13% children, and 8.4% adults are influenced with asthma. The findings from population-based surveys have disclosed that around 2 to 4% annual increase is observed in asthma cases in Europe in last two decades (Lahdensuo et al., 1996). Smoking acts as a chief barrier while fighting for the global burden of asthma. According to the surveys conducted by To et al., in a multicenter study estimated 4.3% adults suffer from asthma. The highest rate of prevalence is found in Australia (21.5%), Sweden (20.2%), United Kingdom (18.2%), Netherlands (15.3%), and Brazil (13.0%). Though asthma mortality rate is decreasing worldwide but asthma in children is increasing (To et al., 2012).
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